Add unit test for at least one previously mistreated formula

Use ExcelNumberFormat library to format strings.

Merge pull request #583 from dhnc4u/develop ...

Invalid Print Area fix (issue 578)

Invalid Print Area fix (issue 578) ...

The modified code will not try to add an (invalid) print area to an unnamed worksheet, avoiding the unhandled exception.

Sorted methods/fields alphabetically according to CodeMaid conventions

Merge pull request #576 from jongleur1983/FunctionsAndTests-MathTrigStartingWithCtoF ...

Functions and tests math trig starting with C to F

separate test cases for FLOOR.MATH ...

this would allow easier detection of what's failing and follows the principle of one assertion per test.

improve FACTDOUBLE and add unit tests ...

FACTDOUBLE now throws correct exceptions and

improve Fact (throw correct exceptions on invalid input), add unit tests

add unit test for EXP function

unit tests for EVEN

unit tests for DEGREES function

add unit testeds for COSH

add unit tests for COS

improve COMBIN and add unit tests ...

COMBIN did not handle non-numeric values correctly. Should throw NumberException (#NUM in Excel). Returned 0 for any non-numeric parameter instead before

Merge pull request #572 from jongleur1983/feature/functionsAndTests-MathTrigStartingWithAtoB-exceptAggregate ...

Add all missing functions starting with A and B, except AGGREGATE

implement BASE and corresponding unit tests

throw correct exceptions on ATANH and add unit tests

fix ATAN2 implementation and add tests ...

Math.Atan2() expects y as first parameter and x as second, while in Excel x is first,
throw "correct" exception on input (0, 0)

add unit tests

Merge pull request #570 from b0bi79/outofmemory ...

OutOfMemoryException. Some range disposing.

OutOfMemoryException. Some range disposing.

add unit tests for ATAN function

add unit tests for ASINH

improve ASIN: throw NumberException for values not in range for Excel ...

...add unit tests for ASIN

implement ARABIC and unit tests

restrict valid input range to [1..) as in Excel, add unit tests.

fix ACOS implementation: in Excel only defined in range [-1, 1] ...

if input is not in range, throw exception.

adding unit tests for ACOS

ABS was implemented already, adding unit tests.

Merge remote-tracking branch 'ClosedXML/develop' into develop

Merge pull request #568 from jongleur1983/feature/RestrictCSharpVersion ...

Feature/restrict c sharp version